The present invention relates to a clamping device and more particularly, to a clamping device for clamping or connecting plate-like members such as corrugated boards and the like especially used, for example, for sealing flap covers of packing cases, etc.
Commonly, it has been a general practice to seal or clamp flap covers of a packing case by applying thereto adhesive tapes, or by winding strings around a plurality of pairs of small disc members respectively fixed to the flap covers by eyelets or rivets for connecting the flap covers together, or by driving staples into the flap covers by staplers.
The conventional means as described above, however, have disadvantages in that to open the packing case thus sealed is troublesome, or re-sealing is difficult once the packing case is opened, or even if re-sealing is possible, troublesome procedures are required therefor.
By way of example, in the packing cases the flap covers of which are sealed by adhesive tapes, surfaces of corrugated boards constituting the packing case are inevitably damaged when the adhesive tape is peeled off, and a new adhesive tape must be used, for sealing the flap covers again. Meanwhile, in the arrangement in which strings are passed around the pairs of small discs fixed to the flap covers, much labor is required for assembly of the packing case due to the increased number of parts involved, and moreover, the work in winding the strings around the discs during sealing is difficult to be effected by automation. Similarly, in the practice of driving the staples into the flap covers by a stapler, although the sealing of the flap covers may be effected efficiently by the use of the stapler, it is necessary to pull the flap covers up with a considerable force for opening the packing case, with consequent breakage or damage to the flap covers, when the packing case is opened, and furthermore, the re-sealing of the packing case can not be effected by hand, but again requires the use of the stapler.
More specifically, referring to FIGS. 1 to 3 showing the conventional practice as described in the foregoing, in the arrangement of FIG. 1, for example, two pairs of small discs 4 and 5 are fixed to the flap covers 2 and 3 of a packing case 1 for winding strings 6 around the small discs 4 and 5, and in FIG. 2, staples 7 are applied by a stapler (not shown) to the flap covers 2 and 3 of the packing case 1 across the junction j therebetween, while in FIG. 3, the adhesive tape 8 is applied over the flap covers of junction j of the packing case 1 as shown.
Although the re-sealing is simply effected in the arrangement of FIG. 1, the strings 6 tend to come loose or come off the small discs during transit or handling of the packing case 1, while in FIGS. 2 and 3, the surfaces of the flap covers 2 and 3 are inevitably damaged and new staples or adhesive tape are required for re-sealing as mentioned earlier.